Osaka Extrusive Rocks 2000ml
Pond water is filtered by denitrifying bacteria. This highly beneficial bacteria need a body to do their job well. Osaka Extrusive Rocks is very porous and therefore the best material to use in the pond filter. There can be formed a lot of bacteria cultures in this filter material!
There are several types of 'knock-off'' substrate on the market, but Osaka Extrusive Rocks is a substrate which is 100% natural. There is no production to adapt and therefore are there in Osaka Extrusive Rocks also not polluting industrial substances such as heavy metals and obsidian.
Osaka Extrusive Rocks is the purest substrate that you can use in the pond filter.